1. Field of the Invention
The present invention relates to a method of making or producing an end of an optical fiber bundle, in which a sleeve is placed or mounted onto an end section of the optical fiber bundle and the sleeve is pressed in a shaping tool at least while exerting pressure on the end section. The present invention also relates to an apparatus for making or producing the end of the optical fiber bundle with the sleeve, which comprises a holder for holding the end section of the optical fiber bundle and a shaping or pressing tool, in which the sleeve can be pressed against the end section of the optical fiber bundle.
2. Related Art
Frequently a flexible light guide comprising a plurality of individual optical fibers, a so-called optical fiber bundle, is used for light transmission. The individual optical fibers are usually fastened together in a common end in a sleeve, which, for example, is fixed to a light source serving for illumination.
It is known to bond the individual optical fibers with each other by adhesive and with a sleeve that is pushed on them or alternatively by melting the individual optical fibers together in the common sleeve.
JP 3144601 describes a method, with which the end of an optical fiber bundle can be provided. For this purpose the optical fiber bundle end is heated and inserted into a narrowing or constricting opening. The diameter of the bundle is reduced in that way and the bundle is compressed together.
DE 2 630 730 A1 describes a method that begins in the same manner. In this method the end of the optical fiber bundle is similarly inserted into a metallic sleeve. The fiber optic bundle together with the sleeve is then pushed into a narrowing or constricting hole, which is provided in a pressing member. The end of the optical fiber bundle is shaped by means of the sleeve by moving the end of the fiber optic bundle equipped with the sleeve in an axial direction while simultaneously heating.
DE 19 855 958 A1 similarly provides a method in which the terminal region of an optical fiber bundle is equipped with a metallic sleeve and subsequently held in a clamping apparatus. A shaping tool with a decreasing or narrowing inner diameter moves in an axial direction on the sleeve and converts the fiber ends into a hexagonally packed arrangement by heat transfer. There is a gap between the inner wall of the shaping tool and the sleeve, in which the heat transfer to the ends of the optical fibers occurs by means of an annular section at the front end of the optical fiber bundle. The conversion process is conducted so that no glass seal is formed between the optical fiber bundle and the metallic sleeve.
This process has the disadvantage that an axial force must be exerted on the optical fiber bundle when it is inserted in the sleeve, which can lead to damage at least to the outer optical fibers of the bundle. Furthermore the sleeve must have suitable stability, so that a material like steel must be selected for it or a large wall thickness is required.
In the methods described in DE 32 47 500 A1 and DE 37 44 367 C1 melted glass is injected around a glass fiber bundle arranged in a sleeve by means of an annular injecting means. The apparatuses performing these methods are comparatively expensive.
According to GB 1 595 163 a thermoplastic terminal sleeve is bonded to the thermoplastic protective jacket of the optical fiber bundle by ultrasonic welding using a two part sonotrode and to the optical fiber bundle.
U.S. Pat. No. 3 914 015 describes a fiber binder. The end sleeve inserted in this fiber binder comprises a shrinkable metal, which is shrunk onto the fiber ends at a temperature of about 75° C.
U.S. Pat. No. 5 222 180 describes a process for making a terminating member for a fiber bundle made from polymer fibers. The fibers are drawn cold, inserted in a sleeve and then heated. During heating they attempt to regain their original shape and fill the sleeve cross-section.